Ultrasonic Testing

Ultrasonic testing (UT) comprises a range of non-destructive testing (NDT) techniques that send ultrasonic waves through an object or material. These high frequency sound waves are transmitted into materials to characterise the material or for flaw detecting. Most UT inspection applications use short pulse waves with frequencies ranging from 0.1-15 MHz, although frequencies up to 50 MHz can be used. One common application for this test method is ultrasonic thickness measurement, which is used to ascertain the thickness of an object such as when assessing pipework corrosion.

How does it Work?

Ultrasonic inspection uses a piezoelectrictransducer connected to a flaw detector, which in its most basic form is a pulser-receiver and oscilloscope display. The transducer is passed over the object being inspected, which is typically coupled to the test object by gel, oil or water. This couplant is required to efficiently transmit the sound energy from the transducer into the part, however This couplant is not required when performing tests with non-contact techniques such as electromagnetic acoustic transducer (EMAT) or by laser excitation.

Advantages of ultrasonic testing:

• High penetration power, allowing for flaw detection deep within a part.
• High sensitivity, allowing for the detection of very small flaws
• Can be used to test when only one side of an object is accessible
• Greater accuracy, when compared to other non-destructive testing methods, for determining depth of internal flaws and the thickness of parts with parallel surfaces
• Able to estimate size, shape, orientation and nature of defects
• Able to estimate alloy structures of components with differing acoustic properties
• Non-hazardous to nearby personnel, equipment or materials
• Highly automated and portable operations possible
• Immediate results can be obtained, allowing for immediate decisions to be made